To mitigate the negative impacts of global warming, international community has issued policies to accomplish carbon emission peak and carbon neutrality by 2030s and mid-21st century, respectively. Using projections from the Coupled Model Intercomparison Project Phase 6, this study compares differences of future climate change risks between under carbon peaking and carbon neutrality goals and under higher scenarios based on the signal-to-noise (SNR) method. By the level of climate change risks, the respective climate conditions can be sorted as "unusual" (SNR≥1), "unfamiliar" (SNR≥2) and "unknown" (SNR≥ 3). Under the low emission scenario, in the near-term future most regions of the earth will face "unusual" climate conditions, nearly simultaneously comparable with higher scenarios due to minor differences in CO₂ emissions between different scenarios, except in some regions where reductions of aerosol emissions will dominate on the local surface air temperature (SAT) change. However, in the mid-term and long-term future, for the fast decrease in CO₂ emission under carbon emission peaking and neutrality goals, almost all the globe will be exposed to an "unfamiliar" or "unusual" climate condition several decades later even beyond 2100 than under higher scenarios. In addition, mitigation will make the percentage of surface area exposed to higher climate change risks 30~60% lower than those under higher emission scenarios. Therefore, decision-makers should attach more importance to the climate penalty induced by decreased aerosols and take regional characteristics of climate change into consideration for developing more effective adaptation and mitigation strategies.

carbon peaking and carbon neutrality goals  /  climate change risk  /  global warming  /  signal-to-noise ratio (SNR)  /  time of emergence (ToE)